Ultradyne UD Butt Stock Spacer Kit Black. Four sets of screws are sent with the kit for proper installation no matter the number of spacers in use. The kit is compatible with the UD Lightweight Butt Stock and UD Picatinny Stocks. Specifications for Ultradyne UD Butt Stock Spacer Kit: Manufacturer: Ultradyne Color: Black Stock/Brace Material: Nylon Fabric/Material: Nylon Length: 0.25 in Weight: 3.52 oz Features of Ultradyne UD Butt Stock Spacer Kit All Hardware Included Nylon 12 for light weight Quarter inch adjustment increments Package Contents: Ultradyne UD Butt Stock Spacer Kit Installation Hardware Included Ultradyne UD20182: UD Butt Stock Spacer Kit Black